(a) Field of the Invention
The present invention relates to a thin film transistor array panel.
(b) Description of the Related Art
Generally, a liquid crystal display (LCD) includes two panels provided with electrodes and a liquid crystal layer interposed therebetween and controls light transmittance by adjusting the magnitude of the voltages applied to the electrodes.
The LCD includes a plurality of pixels for displaying images. The pixels are arranged in a matrix and each pixel includes a pixel electrode made of a transparent conductive material. The pixel electrodes are driven by signals from a plurality of signal lines including a plurality of gate lines and a plurality of data lines. The gate lines and the data lines intersect each other to define a plurality of pixel area arranged in a matrix and connected to the pixel electrodes through a plurality of switching elements such as thin film transistors (TFTs). The switching elements selectively transmit image signals from the data lines in response to the scanning signals from the gate lines. Each pixel further includes a storage electrode forming a storage capacitor along with the pixel electrode for maintaining the image signal applied to the pixel electrode until the next signal is applied thereto.
A pixel defect generated in a manufacturing process of an LCD having TFTs is one of the factors increasing the product cost. Since a white defect of the pixel defect that a pixel is always bright is easily recognized, it is preferable that the white defect is repaired to be converted into an indistinguishable black defect that a pixel is always dark.
A kind of origins of the white defect is the poor contact between a pixel electrode and a switching element or the malfunction of the switching element. In this case, although the defected pixel initially displays a black state, it is gradually changed into a white defect as time goes due to the current leakage of the pixel electrode, which makes the voltage of the pixel electrode reach a common voltage of a common electrode facing the pixel electrode. Alternatively, the white pixel is resulted from the short circuit between a data line and a pixel electrode via a conductor remnant or from the short circuit between a common electrode and a pixel electrode.
One of conventional repairing methods for converting a white defect into a black defect short-circuits a pixel electrode with a gate line overlapping the pixel electrode to form a storage capacitor and transmitting a gate signal to a switching element of pixels in an adjacent row such that the pixel electrode is supplied with the gate signal from the gate line.
However, a thick insulating layer with thickness of two to four microns interposed between the pixel electrode and the gate line obstructs the laser short circuit therebetween. Furthermore, the white defect of an independent wire type LCD having storage electrodes overlapping pixel electrodes may not be repaired by short-circuiting a defected pixel electrode and a storage electrode overlapping the pixel electrode since the storage electrode is supplied with a common voltage.